[Sugar-devel] Communication between two Activities

[Gustavo Duarte]

James,

thank you very much, for your clear explanation.
El 20/05/2015 20:07, "James Cameron" <quozl at laptop.org> escribió:

> On Wed, May 20, 2015 at 10:43:23AM -0300, Gustavo Duarte wrote:
> > Notificator: There is a Sugar Activity who shows Notification messages
> > for the kid.
> >
> > Daemon: There is an script running on cron, who get new notification
> > from a Server.
> >
> > I need communicate the Daemon with the Notificator, so when Daemon
> > receive a new notification from Server, it'll send a signal to
> > Notificator.
> >
> > Notificator when receive the signal, should refresh a widget.
> >
> > I know a way to do that, using system signals, but i wonder if Sugar
> > has another way to achieve that.
>
> What you describe is interprocess communication.
>
> Sugar uses several methods for communication with system daemons.
>
> The most frequently coded is D-Bus.
> http://en.wikipedia.org/wiki/D-Bus
>
> Other methods in Python are
> https://docs.python.org/2/library/ipc.html
>
> You can use files, as Gonzalo says, but try to place them in a path
> that does not cause writes to disk; e.g. /tmp ... otherwise sometimes
> the kernel will reschedule the process that is writing, and this can
> slow performance.
>
> My preference for your scenario is signals:
>
> 1.  Notificator calls os.getpid and writes to /tmp/notificator.pid
>
> 2.  Notificator calls signal.signal to request a callback on SIGUSR1,
>
> 3.  Daemon reads /tmp/notificator.pid and calls os.kill(pid, SIGUSR1),
> kill(1), or kill(3) to send signal.
>
> An example here:
> http://dev.laptop.org/git/projects/runin/tree/runin-gtk
>
> Signals become more complex if the communication is complex, and there
> are a limited number of different signals.  That's when I would
> suggest D-Bus.
>
> --
> James Cameron
> http://quozl.linux.org.au/
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sugarlabs.org/archive/sugar-devel/attachments/20150522/e83ebc20/attachment.html>